Rock & Mineral Encyclopedia

Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.

Greywacke

A hard, dark, poorly sorted sandstone with a muddy matrix, typically deposited by underwater turbidity currents.

A green ornamental stone, often serpentine-rich marble or verde antique, valued for its rich green color and white veining.

A feldspar-rich sandstone, often pink, that points to granitic source rocks eroded quickly in dry or cold climates.

A rare strontium-dominant feldspar, the strontium analogue of paracelsian, found in metamorphosed strontium-rich and manganese-bearing rocks.